SMD capacitor are not available for loose-structured solid dielectrics, many of which are glass dielectrics or ceramics with poor dielectric properties, because they have loose structures, contain impurities, and have many lattice defects. Some weak electrons or ions are bound in the medium. Like charged particles, thermal motion makes the distribution of these weakly charged particles disorderly.
For SMD capacitor, under the action of an external electric field, some weakly charged particles begin to be arranged according to the electric field. At a certain temperature, this trend of arranging the electric field and the thermal motion at that temperature reach a dynamic balance, resulting in relaxed polarization, including ion relaxed polarization and electronic relaxed polarization. The process of establishing relaxed polarization is accompanied by energy loss. As the temperature T of the SMD capacitor changes, the degree of ease of relaxation of polarization will also change.
In addition, it takes a certain time for the ion relaxation polarization to be established, and it may be too late for the SMD capacitor frequency f to be established. Therefore, the dielectric constant ε generated by the relaxation polarization will also depend on the temperature T and the frequency f. Strictly speaking, all ionic structure dielectrics contain more or less impurities and defects. Therefore, any inorganic dielectric material has this kind of relaxed polarization mode, but the degree is different. When the relaxed polarization of the ions in a certain dielectric material constitutes the main polarization mode, the loss of this type of material will be greater and the stability will deteriorate. Certain ceramics and glasses belong to this type of substance.